1. Field of the Invention
The present invention relates to a hook assembly for use in a shadow mask frame assembly and in particular to a hook assembly that attaches a shadow mask frame to the face panel of a CRT. The present invention also relates to a shadow mask frame assembly with such a hook assembly.
2. Description of the Related Art
A shadow mask frame assembly for use in flat CRT comprises a pair of support bars 11,12, a pair of tension bars 13 and 14 of which ends are welded to an each end of the support bars 11 and 12, a shadow mask 20 supported by the support bars 11 and 12 and a plurality of hook assembly 9 attached to the support bars 11 and 12 and/or the tension bars 13 and 14, as shown in FIG. 1. Also, as shown in a circle indicated by xe2x80x9cAxe2x80x9d, there are provided with plurality of slots 22 between strips 21 connected with tie bars 23.
The shadow mask frame assembly is installed in the face panel of the flat CRT by means of the hook assembly 9. More specifically, it is installed in the face panel by inserting stud (not-shown) formed on the inner surface of the skirt portion of the face panel into the hole 28 of the hook assembly 9, comprising base 26 and a spring 27, welded on the support bars 11 and 12 and the tension bars 13 and 14 of a shadow mask frame, as illustrated in FIG. 1.
FIG. 2 is an exploded view of the hook assembly 9 further showing welding points. The hook assembly is firmly attached to the support bars11 and 12 and/or the tension bars 13 and 14 of a mask frame by spot welding at a couple of points 29, i.e., on the part of the base 26. Welding must be very strong because the metallic mask frame is rather heavy. The more so recently since flat panel CRTs use relatively heavier frames. The base 26 of the hook assembly 9 welded on the bars is thick and may suffer heat-induced deformation. For instance, while hook assembly is being welded at one spot it may deform so that the next welding point can be off its spot. The deformed hook assembly results in welding weaker than desired and can cause the mask to shift from intended position.
It is an objective of the present invention to provide a hook assembly that is less deformable subjected to heat such that the hook assembly can be attached by welding to the predetermined location of the mask frame without error.
The objective is achieved by proving a buffer zone in the middle of a base of the hook assembly in a variety of ways so that possible deformation of the hook assembly at one part during welding can prevented from spreading to the rest of the hook. The buffer zone may be tunnel like arch or indention.